Comparative preventive efficacy of ProHeart® 12, Heartgard® Plus and Interceptor® Plus against a macrocyclic lactone-resistant strain (JYD-34) of heartworm (Dirofilaria immitis) in dogs

Table 4 Study 2: Efficacy of ProHeart 12 compared to Heartgard Plus or Interceptor Plus against the JYD-34 heartworm strain: Day 165 inoculation, adult heartworm AG and MF results

Treatment	Dosage	Days of treatment	Number of infected dogs^{a, b}	No. dogs positive for adult heartworm AG^c		No. dogs positive for MF
Treatment	Dosage	Days of treatment	Number of infected dogs^{a, b}	Day 331 (day 166 PI)	Day 360 (day 195 PI)	Day 331 (day 166 PI)	Day 360 (day 195 PI)
Negative control	NA	0	6 of 6	6 of 6^d	6 of 6^e	0 of 6	5 of 6
ProHeart 12	0.5 mg/kg moxidectin^f	0	4 of 6	0 of 6^g	1 of 6^h	0 of 6	0 of 6
Heartgard Plus	Min. of 6 µg/kg ivermectinⁱ	0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330	6 of 6	6 of 6^j	6 of 6	0 of 6	5 of 6
Interceptor Plus	Min. of 0.5 mg/kg milbemycin oxime^k	0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330	6 of 6	6 of 6^l	6 of 6^m	0 of 6	5 of 6

^aEach dog was inoculated with 50 D. immitis third-stage larvae (JYD-34 strain) on day 165
^bAll dogs were necropsied for recovery of adult D. immitis on day 360 (195 days PI; 30 days after the last treatment with Heartgard Plus and Interceptor Plus)
^cDiroCHEK
^d Two of six dogs positive only after heat treatment; positive on both DiroCHEK and Snap4DX
^eOne of six dogs positive only after heat treatment; positive on both DiroCHEK and Snap4DX
^f ProHeart 12 (moxidectin extended-release injectable suspension) administered according to commercial label directions which resulted in a point administration of 0.5 mg/kg of moxidectin to each dog
^gAll six of the dogs remained Ag-negative after samples were heat treated
^hOne dog with a single male worm was slightly positive only after heat treatment; positive on both DiroCHEK and Snap4DX
ⁱHeartgard Plus (ivermectin + pyrantel) administered according to commercial label directions which resulted in administration of 6.5 to 11.5 µg/kg of ivermectin
^jThree of six dogs positive only after heat treatment; positive on both DiroCHEK and Snap4DX
^kInterceptor Plus (milbemycin oxime + praziquantel) administered according to commercial label directions which resulted in administration of 0.51 to 1.1 mg/kg milbemycin oxime
^lFive of six dogs positive only after heat treatment; positive on both DiroCHEK and Snap4DX
^mOne of six dogs positive only after heat treatment; positive on both DiroCHEK and Snap4DX

ISSN: 1756-3305